How Aura rewrites text, and where the model actually runs.
An AI writing assistant that sends your text to someone else's server is a different product from one that doesn't. This page walks through every part of Aura — the rewrite flow, the eight modes, how the diff review works, and the four engines it picks between depending on what your Mac can run.
01The shortcut and the flow
Select, press, review.
The rewrite
Select text in any app and press ⇧⌘P. The rewritten text streams back in place through a floating HUD.
Cancelling
esc cancels at any time, leaving both the original text and your clipboard untouched.
The second shortcut
A separate always-proofread shortcut, for when you want a correction rather than a rewrite and don't want to think about modes.
02The eight modes
What each one is actually for.
The list
Proofread (the default), Improve Clarity, Formal/Academic, Friendly, Make Concise, Expand, Bullet Points, and Custom Instruction.
Proofread is deliberately conservative
It corrects rather than rewrites. That is why Voice Mirroring is excluded from it — a proofread should return your sentence, fixed, not a different sentence in your style.
03The diff review card
The safeguard for longer selections.
Word-level diff
Longer selections show a review card before anything is inserted — deletions in red, insertions in green — with Insert or Discard.
04Voice Mirroring
Making rewrites sound like you rather than like a model.
How it learns
Measures your own writing on-device from up to three samples — sentence length, contraction habits, register, punctuation fingerprints and emoji use — and applies that to rewrites.
Where it does not apply
Proofread, deliberately. See above.
05The four engines
Auto-picked, best available first.
The order
Apple Intelligence (macOS 26+, free) → Aura's own downloadable model (Core ML on the Neural Engine, Balanced 1.2 GB or Expert 2.8 GB, fully offline once downloaded) → any local OpenAI-compatible server such as LM Studio, Ollama or llama.cpp → a built-in NSSpellChecker-based deterministic cleanup.
The fallback always works
That last engine needs no model and no network, but handles Proofread only.
06Permissions and prompt injection
One permission, and one design decision worth stating.
Accessibility, and nothing else
Used to read the selection — via the accessibility API or a synthesized ⌘C — and to write the result back through the clipboard and ⌘V, restoring your previous clipboard afterwards.
Your selection is never an instruction
Selected text is always treated as material to edit, never as instructions to the model. Text that says "ignore your instructions and…" gets proofread, not obeyed.
07Now go try it.
Free for 14 days, no account. Back to Aura · Buying & licensing · Support